With increasing use of smart devices, especially wearable devices in people's life, power management of these devices becomes a relatively prominent problem. For example, when a user wants to go to a gymnasium for many times, a wristband displays a red-yellow light to prompt that the wristband should be charged. For example, some smart devices can deliver a prompt when power is low; however, a case usually appears that no prompt is delivered when a user pays attention, but a prompt is delivered when the user pays no attention; for example, no prompt is given before an owner goes to sleep (power still does not reach a lowest limit, and therefore no prompt is given), but a charging prompt is given after the owner falls asleep.
A principle of a method for displaying power of a Bluetooth device on a Bluetooth mobile phone in the prior art is as follows: The Bluetooth device periodically calculates remaining power of the device, and then sends the remaining power to the Bluetooth mobile phone; the Bluetooth mobile phone determines whether the foregoing remaining power is greater than a set threshold; if a calculation result is greater than the set threshold, the remaining power of the Bluetooth device is displayed on a screen of the Bluetooth mobile phone; and if the calculation result is less than the set threshold, the remaining power of the Bluetooth device is displayed on the screen of the Bluetooth mobile phone, and an alarm is given.
A problem existing in the prior art is that a Bluetooth device needs to periodically detect power, but the power is sufficient in most cases, and therefore such detection is unnecessary and causes a waste of resources.